Method of assembling gas turbine engine section

ABSTRACT

A method for assembling a section of a gas turbine engine is disclosed. The method involves aligning a vane ring with a first rotor hub such that a row of vanes on the vane ring is adjacent a first row of blades of the first rotor hub, and aligning a second rotor hub with the vane ring such that a second row of blades of the second rotor hub is adjacent the row of vanes and the row of vanes is axially between the first row of blades and the second row of blades. The first hub and the second hub are then non-mechanically bonded together.

CROSS-REFERENCE TO RELATED APPLICATION

The present disclosure is a continuation of U.S. patent application Ser.No. 14/607,301, filed Jan. 28, 2015.

BACKGROUND

A gas turbine engine typically includes a fan section, a compressorsection, a combustor section and a turbine section. Air entering thecompressor section is compressed and delivered into the combustionsection where it is mixed with fuel and ignited to generate a high-speedexhaust gas flow. The high-speed exhaust gas flow expands through theturbine section to drive the compressor and the fan section. Thecompressor section typically includes low and high pressure compressors,and the turbine section includes low and high pressure turbines.

The high pressure turbine drives the high pressure compressor through ahigh spool, and the low pressure turbine drives the low pressurecompressor through a low spool. The fan section may also be driven bythe low spool. A direct-drive gas turbine engine includes a fan sectiondriven by the low spool, without a gear mechanism, such that the lowpressure compressor, low pressure turbine and fan section rotate at acommon speed.

SUMMARY

A method for assembling a section of a gas turbine engine according toan example of the present disclosure includes aligning a vane ring witha first rotor hub such that a row of vanes on the vane ring is adjacenta first row of blades of the first rotor hub, aligning a second rotorhub with the vane ring such that a second row of blades of the secondrotor hub is adjacent the row of vanes and the row of vanes is axiallybetween the first row of blades and the second row of blades, andnon-mechanically bonding the first hub and the second hub together.

In a further embodiment of any of the foregoing embodiments,non-mechanically bonding the first hub and the second hub togetherincludes metallurgically bonding the first hub and the second hub.

A method for assembling a section of a gas turbine engine according toan example of the present disclosure includes aligning variable vanes ona vane ring with a corresponding one of a plurality of throat regions ofan end row of blades of a multi-row rotor drum and moving the vane ringsuch that the variable vanes move through the plurality of throatregions past the end row into a position axially between the end row anda next row of blades of the multi-row rotor drum.

In a further embodiment of any of the foregoing embodiments, themulti-row rotor drum is formed of a single-piece body that has aplurality of rows of blades.

In a further embodiment of any of the foregoing embodiments, thealigning includes adjusting the variable vanes in unison.

In a further embodiment of any of the foregoing embodiments, thealigning includes adjusting the variable vanes individually.

In a further embodiment of any of the foregoing embodiments, thealigning includes adjusting the variable vanes using an assembly tool.

In a further embodiment of any of the foregoing embodiments, moving thevane ring axially and circumferentially to navigate the variable vanesthrough the throat regions free of contact with the blades of the endrow.

A further embodiment of any of the foregoing embodiments includespivoting the variable vanes to navigate the variable vanes through thethroat regions free of contact with the blades of the end row.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the present disclosure willbecome apparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

FIG. 1 illustrates an example gas turbine engine that has a direct-driveengine architecture.

FIG. 2 illustrates an example multi-row rotor drum of a low compressorsection.

FIG. 3 illustrates an example split vane assembly.

FIG. 4 illustrates an example overlapping joint of a split vaneassembly.

FIG. 5 illustrates an example sealed joint of a split vanes assembly.

FIG. 6 illustrates an example split vane assembly with arc segments thathave end portions that are stronger than intermediate portions of thearc segments.

FIG. 7 illustrates an example multi-row rotor drum that is assembledfrom two hub sections that are bonded together.

FIG. 8 illustrates an example of a vane ring that is assembled onto amulti-row rotor drum by sliding variable vanes through the throatregions between blades of an end row of the rotor.

FIG. 9 illustrates an example of a vane ring that is assembled onto amulti-row rotor drum by sliding variable vanes axially andcircumferentially.

FIG. 10 illustrates an example of a vane ring that is assembled onto amulti-row rotor drum by pivoting variable vanes.

FIG. 11 illustrates an example vane ring that is assembled onto amulti-row integrally bladed rotor drum, where at least one row of bladesis secured to, or fabricated in-situ on, the multi-row integrally bladedrotor drum.

FIG. 12 illustrates an example continuous hoop vane ring.

FIG. 13A illustrates another example continuous hoop vane ring.

FIG. 13B illustrates a cross-section of the continuous hoop vane ring ofFIG. 13A after insertion of a vane.

FIG. 14 illustrates an example of a gas turbine engine with a case thathas a first section and a second, hoop section aft of the first section.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20 (“engine 20”).The engine 20 has a direct-drive engine architecture. Unlike a gearedengine architecture that drives the fan through a gear mechanism tochange the rotational speed of the fan relative to the driving portionof the turbine, a direct-drive engine architecture drives the fanwithout such a gear mechanism such that the fan rotates at the samespeed as the driving portion of the turbine.

The engine 20 is a two-spool arrangement that generally includes a fansection 22, a compressor section 24, a combustor section 26, and aturbine section 28. In this example, these sections are arrangedserially along engine central axis A with respect to flow through theengine 20, although the examples herein may also be applicable toreverse-flow arrangements and other multi-spool arrangements, such asthree-spool arrangements.

The engine 20 includes a first (or low) spool 30 and a second (or high)spool 32 mounted on bearing systems 38 for concentric rotation about theengine central axis A relative to an engine static structure 36.Although the bearing systems 38 are shown at various locations, theselocations can vary as appropriate to the engine design, and fewer oradditional bearing systems 38 may be provided. The first spool 30 may bereferred to as a low speed spool and the second spool 32 may be referredto as a high speed spool, relative to the speed of the low speed spool.

The compressor section 24 includes a low compressor section 24 a and ahigh compressor section 24 b, and the turbine section 28 includes a lowturbine section 28 a and a high turbine section 28 b. The low compressorsection 24 a may also be referred to as a low pressure compressor andthe high compressor section 24 b may be referred to as a high pressurecompressor, relative to pressure in the low pressure compressor.Likewise, the low turbine section 28 a may also be referred to as a lowpressure turbine and the high turbine section 28 b may be referred to asa high pressure turbine, relative to pressure in the low pressureturbine.

The low compressor section 24 a and the high compressor section 24 binclude, respectively, rows of rotatable compressor blades 40 a and 40 bthat are interleaved with rows of static compressor vanes 42 a and 42 b.A row of compressor vanes and an adjacent row of compressor blades are acompressor stage.

The low turbine section 28 a and the high turbine section 28 b include,respectively, rows of rotatable turbine blades 44 a and 44 b that areinterleaved with rows of static turbine vanes 46 a and 46 b. A row ofturbine vanes and an adjacent row of turbine blades are a turbine stage.In this example, the low turbine section 28 a has four stages. In otherexamples, the low turbine section 28 a may have three or fewer stages.In other examples, the low turbine section 28 a may have more than fourstages such as, for example, five, six, or seven stages.

The fan section 22 includes at least one row of fan blades 22 a. A case48 extends around the fan section 22 and bounds an outer periphery of abypass passage 50. The fan blades 22 a are located generally at theinlet of the bypass passage 50. One or more rows of guide vanes 52 canbe provided downstream from the fan blades 22 a. The guide vanes 52extend between the case 48 and the static structure 36.

The combustion section 26 includes a combustor 54. In this example, thecombustor 54 is arranged axially between the high compressor section 24b and the high turbine section 28 b.

The first spool 30 directly couples the low turbine section 28 a withthe low compressor section 24 a and the fan section 22. The second spool32 couples the high turbine section 28 b with the high compressorsection 24 b. Since there is no gear mechanism in the interconnectionbetween the low turbine section 28 a and the fan section 22, the engine20 is a direct-drive engine architecture, and the fan section 22 willrotate at the same rotational speed as the low turbine section 28 a.

The compressor section 24, the combustor section 26, and the turbinesection 28 form a core engine, which drives the fan section 22. Thecompressor section 24 drives core air C along a core flow path throughthe low compressor section 24 a and then the high compressor section 24b. Compressed air from the high compressor section 24 b is mixed withfuel and burned in the combustor 54 to generate an exhaust gas stream.The exhaust gas stream is expanded through the high turbine section 28 band then the low turbine section 28 a. The expansion over the highturbine section 28 b rotationally drives the second spool 32 to thusdrive the high compressor section 24 b. The expansion over the lowturbine section 28 a rotationally drives the first spool 30 to thusdrive the low compressor section 24 a and the fan section 22. Therotation of the fan section 22 drives bypass air B through the bypasspassage 50 (to provide a significant amount of the thrust of the engine20) and core air C to the low compressor section 42 a.

One characteristic of a turbofan engine is the bypass ratio of theturbofan engine. The bypass ratio is the ratio of the amount of air thatpasses through the bypass passage 50 as bypass air B to the amount ofair that passes through the core engine as core air C at a givenperformance point. Typically a direct drive turbofan engine will not beable to exceed a bypass ratio of about 8 due to engine performancelimitations. However, according to an embodiment, the core engineincludes a bypass ratio of 8.5-11 even without a gear and with an enginehas a thrust rating equal to or less than 40,000 pounds. In one furtherembodiment, the thrust rating is from 30,000 pounds to 40,000 pounds,and the overall pressure ratio (“OPR”) is approximately 40 toapproximately 50. The OPR is the ratio of stagnation pressure at theinlet of the fan section 22, such as at P₁ in FIG. 1, to the stagnationpressure at the outlet of the high compressor section 24 b, such as atP₂ in FIG. 1. The performance point for determining the overall pressureratios herein is the flight condition at the top of climb prior toleveling off for cruise flight condition. The performance point fordetermining the bypass ratios herein is a particular flightcondition—typically cruise at about 0.8 Mach and about 35,000 feet. Theflight condition of 0.8 Mach and 35,000 ft., with the engine at its bestfuel consumption—also known as “bucket cruise Thrust Specific FuelConsumption (‘TSFC’)”—is the industry standard parameter of mass of fuelbeing burned divided by force of thrust the engine produces at thatminimum point.

In a further example, the fan section 22 (at the root of the fan blades22 a), the low compressor section 24 a and the high compressor section24 b together have an OPR of approximately 40 to approximately 60 In afurther embodiment, enhanced performance can be achieved by including afirst row of turbine blades 46 b of the high turbine section 28 b thathas an operating temperature of approximately 2700° F. to approximately3000° F. (approximately 1482° C. to approximately 1649° C.) at maximumtakeoff thrust, and with an engine that has a thrust rating equal to orless than 40,000 pounds. In one further embodiment, the thrust rating isfrom 30,000 pounds to 40,000 pounds, and the OPR is approximately 40 toapproximately 50. In another example embodiment, the bypass ratio isgreater than 4 and the OPR is greater than 40, and in one additionalexample embodiment the bypass ratio is 8.5-11 and the OPR is greaterthan 55.

In a further example, the row of blades 22 a of the fan section 22 havea fan diameter, D_(fan), the high compressor section 24 b has a finalcompressor blade row prior to the combustor section 26 that has acompressor diameter, D_(comp), and the stages of the low turbine section28 a have a maximum diameter, D_(turb). The fan diameter, the compressordiameter, and the maximum diameter of the low turbine section 28 a havean interdependence represented by a scalable ratio D_(fan)/D_(comp) from3.5 to 5.0 and a scalable ratio D_(fan)/D_(turb) from 1.4 to 1.8, andthe fan diameter is at least 68 inches. The interdependence is such thatthe value of any one of the fan diameter, the compressor diameter, andthe maximum diameter depends on the values of the other two through theabove ratios.

FIG. 2 illustrates selected portions of a further example of the highcompressor section 24 b. In this example, the high compressor section 24b includes a multi-row integrally bladed rotor drum 60 that is formed ofa single-piece body 62. In one example, instead of bonded joints ormechanical joints that are used to secure several hub pieces together,the single-piece body 62 includes no joints. For instance, thesingle-piece body 62 is a single, continuous piece of material. In otherexamples, the multi-row integrally bladed rotor drum 60 includes one ormore bonded joints that serve solely, or at least primarily, to hold themulti-row integrally bladed rotor drum 60 together as a unit. In thiscase, the multi-row integrally bladed rotor drum 60 may include one ormore mechanical joints that supplement the one or more bonded joints. Abonded joint may be a joint that is secured by an adhesive, by pressure,by heat, or a combination thereof, such that there is a distinctboundary or discontinuity between the bonded portions that is at leastmicroscopically discernible. Weld and braze joints are examples ofbonded, metallurgical joints.

The multi-row integrally bladed rotor drum 60 presents a challenge toassembly of the high compressor section 24 b. With single rotors, acontinuous hoop vane assembly can be assembled axially between rotors.However, the single-piece body 62 may not permit this assembly approachbecause the blades would interfere with the vanes of the vane assemblyduring installation; therefore, a different assembly methodology thatmeets this challenge is needed. It is to be understood that the examplesherein are also applicable to a turbine section that includes amulti-row rotor drum. Further, assembly can include assembling sectionsof the high compressor section 24 b into the engine 20 to form the highcompressor section 24 b in the engine 20, or assembling the sections toseparately form the high compressor section 24 b and then assembling thehigh compressor section 24 b into the engine 20.

In one example, the compressor vanes 42 b that are axially between therows of the compressor blades 40 b of the multi-row integrally bladedrotor drum 60 are in a split vane assembly 70, shown in FIG. 3. Thesplit vane assembly 70 includes two 180° arc segments 70 a and 70 b. Thearc segments 70 a/70 b can each be inserted in a radial direction (see“R” FIG. 2) into an assembled position between the rows of thecompressor blades 40 b to provide the row of compressor vanes 42 b. Inone modified example, the arc segments 70 a and 70 b have unequal arclengths. In another example, rather than two arc segments, the vaneassembly 70 could have three or more arc segments, which may have equalor unequal arc lengths, or a combination thereof.

Once in the assembled position, the circumferential ends of the arcsegments 70 a/70 b meet at joints or interfaces. These joints orinterfaces could be locations of weakness and/or locations at which coreair could escape. FIG. 4 illustrates an example overlapping joint 72. Inthis example, the arc segments 70 a/70 b include, respectively, tabs 74a/74 b that overlap with respect to the radial direction R. Theoverlapping joint 72 can serve any or all of several functions,including but not limited to, facilitating alignment of the arc segments70 a/70 b, locking the arc segments 70 a/70 b, and providing labyrinthsealing at the interface. Optionally, one or more alignment pins 75 canalso be used to facilitate axial alignment.

FIG. 5 illustrates another example joint 172. In this disclosure, likereference numerals designate like elements where appropriate andreference numerals with the addition of one-hundred or multiples thereofdesignate modified elements that are understood to incorporate the samefeatures and benefits of the corresponding elements. In this example,the arc segments 170 a/170 b include, respectively, slots 176 a/176 b.The slots 170 a/170 b cooperatively retain a circumferential sealelement 178 in the interface of the joint 172, to reduce the potentialfor the escape of core air. In further examples, at least portions ofthe interfaces can be non-mechanically bonded, such as by weld or braze,to provide sealing. Optionally, one or more alignment pins 175 can alsobe used to facilitate axial alignment.

FIG. 6 illustrates a further example in which arc segments 270 a/270 binclude end portions 280 that are stronger than intermediate portions282 of the arc segments 270 a/270 b. In one example, the end portions280 are made stronger by adding mechanical features, such as increasedthickness of vanes 42 b in the end portions 280 relative to the othervanes in the arc segment 270 a/270 b or features in the end portions 280that allow for structural bonding of the end portions 280 in addition tothe arc segments, as described in FIGS. 4 and 5. In another example, theend portions 280 are made stronger by using a different, strongermaterial for the end portions than the intermediate portions 282. Thestronger end portions 280 resist deflection of the full vane ring at thejoints between the arc segments 270 a/270 b, which may reduce“ovalization” during operational loading.

FIG. 7 illustrates another example multi-row integrally bladed rotordrum 160 that has a single piece body 162. In this example, the singlepiece body 162 includes one or more bonded joints, such as at J₁. Abonded joint may be a joint that is secured by an adhesive, by pressure,by heat, or a combination thereof, such that there is a distinctboundary or discontinuity between the bonded portions that is at leastmicroscopically discernible. For example, the single piece body 162 caninclude a first, forward hub 162 a and a second, aft hub 162 b that arebonded together at bonded joint J₁. Each hub 162 a/162 b includes a rowof the compressor blades 40 b which are bonded to or machined with eachhub 162 a/162 b, with the row of compressor vanes 42 b axially therebetween. Thus, the first hub 162 a can be assembled, followed by axialassembly of a vane assembly, followed by assembly of the second hub 162b, which is then bonded in joint J₁ to the first hub 162 a. In thisregard, the bonded joint permits the use of an axial assembly approach.

As also shown in FIG. 7, the compressor vanes 42 b can be assembled bymoving a vane ring 170 with the compressor vanes 42 b into alignmentwith the first hub 162 a such that the row of vanes 42 b is adjacent thefirst row of blades 40 b. In a further embodiment, the vane ring 170 isa continuous full hoop. The second rotor hub 162 b is then moved intoalignment with the vane ring 170 such that the second row of blades 40 bis adjacent the row of vanes 42 b and the row of vanes 42 b is axiallybetween the first and second rows of blades 40 b. The first hub 162 aand the second hub 162 b are then non-mechanically bonded at bondedjoint J₁. In this regard, the bonded joint J₁ permits the use of anaxial assembly approach.

FIG. 8 illustrates another example in which vanes 142 b of vane ring 270are variable vanes, to permit axial assembly of the vane ring 270 ontothe multi-row integrally bladed rotor drum 60. As can be appreciated,only a few of the variable vanes 142 b are shown, to demonstrate theassembly. It is to be understood that the vane ring 270 is a full hoopwith the variable vanes 142 b circumferentially-spaced there around. Thevariable vanes 142 b can be pivoted about their individual radial axis.In some embodiments, the variable vanes 142 b are interconnected with acommon actuation mechanism such that the variable vanes 142 b aremoveable in unison. For instance, a unison ring can be provided to linkthe variable vanes 142 b such that rotation of the unison ring causeseach variable vane 142 b to pivot about its own radial axis. In otherembodiments, each variable vane 142 b can be moved independently of theother variable vanes 142 b. Further, the variable vanes 142 b can bemoved in an automated fashion using a powered actuator, or the variablevanes 142 b can be moved manually or using a tool, such as a torquewrench or other device.

In this embodiment, the multi-row integrally bladed rotor drum 60includes at its axial end an end row 90 of blades 40 b. The blades 40 bare circumferentially spaced-apart by respective throat regions 92. Toassemble the vane ring 270 onto the multi-row integrally bladed rotordrum 60, each variable vane 142 b is aligned with a corresponding throatregion 92 of the end row 90. For instance, the chords or the variablevanes 142 b are aligned relative to the throat regions 92. The vane ring270 is then moved such that the variable vanes 142 b move through thethroat regions 92 past the end row 90 into an assembled position axiallybetween the end row 90 and a next row (shown at 94) of blades 40 b fromthe end row 90.

In further embodiments, the design of the variable vanes 142 b and themulti-row integrally bladed rotor drum 60 can be adapted to permit theaxial assembly of the variable vanes 142 b past the blades 40 b into theassembled position. For instance, vanes often seal against a portion ofa rotor. In one example, the seal includes a knife edge 271 a providedor formed on the multi-row integrally bladed rotor drum 60 (FIG. 2), andthe variable vanes 142 b include honeycombs 271 b on radially innerdiameters. Alternatively, the honeycomb could be on the rotor and theknife edges on the vanes. A radial clearance gap is provided between theknife edge 271 a and the honeycomb 271 b to permit the honeycombs 271 bof the variable vanes 142 b to move into axial alignment with the knifeedges 271 a (or alternatively the knife edges to move into axialalignment with the honeycomb). The clearance gap can be at least aslarge as dimensional and assembly tolerances to ensure that there is nointerference during assembly.

In another embodiment shown in FIG. 9, the vane ring 270 is movedaxially and circumferentially to navigate the variable vanes 142 bthrough the throat regions 92, with no or little contact with the blades40 b. The axial and circumferential movement is represented at steppedlines 96.

In another example shown in FIG. 10, the variable vanes 142 b arepivoted about their radial axes to navigate through the throat regions92 with no or little contact with the blades 40 b. The pivoting movementis represented at lines 98. Of course, it is also contemplated that thevariable vanes 142 b be pivoted, in combination with also moving axiallyand circumferentially, to navigate through the throat regions 92.

In another example shown in FIG. 11, the blades 40 b of at least one rowof the multi-row integrally bladed rotor drum 60 are initially separatesuch that a full hoop vane ring 370 can be axially assembled over themulti-row integrally bladed rotor drum 60. The blades 40 b of the secondrow are then secured to, or formed on, the multi-row integrally bladedrotor drum 60. In this regard, the blades 40 b can be pre-fabricated andthen secured or, alternatively, fabricated in-situ on the multi-rowintegrally bladed rotor drum 60 using an additive fabrication technique.

FIG. 12 illustrates another example vane assembly 470 for installing therow of compressor vanes 42 b axially between the rows of the compressorblades 40 b of the multi-row integrally bladed rotor drum 60. In thisexample, the vane assembly 470 is a continuous full hoop that includesan annular support 473 with a plurality of vane openings 473 a arrangedaround the circumference thereof. The annular support 473 can bepositioned axially between the rows of rotor blades 40 b, and the vanes42 b can then be inserted radially through the vane openings 473 a. Inthis example, the vanes 42 b are vane multiplets that have two or moreairfoils that are attached to a common platform 475. Each multiplet isassembled into the annular support 470. Alternatively, the vanes 42 bcan be individual vanes that are assembled into the annular support 470individually.

The vanes 42 b are secured to the annular support 473 by mechanicalfastener, bonded joint, or combination thereof. If mechanical, themechanical joint can include a tab that extends from the vane 42 badjacent the annular support 473. The tab and annular support 473 canhave an opening that receives a fastener there through. If bonded, thebonded joint can be a braze joint or a weld joint around the perimeterof the vane 42 b at the interface with the annular support 473.

FIGS. 13A and 13B illustrate another example vane assembly 570 forinstalling the row of compressor vanes 42 b axially between the rows ofthe compressor blades 40 b of the multi-row integrally bladed rotor drum60. In this example, the vane assembly 570 is a continuous full hoopthat includes an annular support 573 with at least one window 577 thatopens radially outwards. The annular support 573 can be positionedaxially between the rows of rotor blades 40 b, and the vanes 42 b canthen be inserted radially through the window 577.

The platforms 575 of the vanes 42 b have opposed hooks 579 that engage aslot 581 at the inner diameter of the annular support 573. The slot 581extends circumferentially around the inner diameter of the annularsupport 573. Each vane 42 b is inserted through the window 577 and intothe slot 581. The hooks 579 engage the slot 581 such that the vane 42 bcan then be slid circumferentially around the slot 581 to its finalassembly position. After all of the vanes 42 b have been inserted andslid to final position, a cover 583 is secured over the window 577. Thecover 583 has a stop portion 583 a that protrudes radially inwards inbetween adjacent vanes 42 b. The stop 583 a circumferentially locks thevanes 42 b in place. Alternatively, the stop portion 583 a can be aseparate piece from the cover 583.

FIG. 14 illustrates another example gas turbine engine 120 that issimilar to the engine 20. In this example, the case 148 is separable topermit a relatively large access work space 100 through the case 148between an exterior of the case 148 and the core engine. The case 148has a first section 148 a and a second, hoop section 148 b aft of thefirst section 148 a. The second section 148 b is axially moveable fromthe first section 148 a to provide the access work space 100. In oneexample, the case 148 includes a track 102 on which the second section148 b is slidable. Lock members 104 a/104 b can be provided toselectively secure the first section 148 a and the second section 148 btogether. For example, the lock members 104 a/104 b include a latch, aV-groove arrangement, or the like, which also ensure axial alignment ofthe sections 148 a/148 b.

Although a combination of features is shown in the illustrated examples,not all of them need to be combined to realize the benefits of variousembodiments of this disclosure. In other words, a system designedaccording to an embodiment of this disclosure will not necessarilyinclude all of the features shown in any one of the Figures or all ofthe portions schematically shown in the Figures. Moreover, selectedfeatures of one example embodiment may be combined with selectedfeatures of other example embodiments.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthis disclosure. The scope of legal protection given to this disclosurecan only be determined by studying the following claims.

What is claimed is:
 1. A method for assembling a section of a gasturbine engine, the method comprising: aligning variable vanes on a vanering with a corresponding one of a plurality of throat regions of an endrow of blades of a multi-row rotor drum; and moving the vane ring suchthat the variable vanes move through the plurality of throat regionspast the end row into a position axially between the end row and a nextrow of blades of the multi-row rotor drum.
 2. The method as recited inclaim 1, wherein the multi-row rotor drum is formed of a single-piecebody that has a plurality of rows of blades.
 3. The method as recited inclaim 1, wherein the aligning includes adjusting the variable vanes inunison.
 4. The method as recited in claim 1, wherein the aligningincludes adjusting the variable vanes individually.
 5. The method asrecited in claim 1, wherein the aligning includes adjusting the variablevanes using an assembly tool.
 6. The method as recited in claim 1,including moving the vane ring axially and circumferentially to navigatethe variable vanes through the throat regions free of contact with theblades of the end row.
 7. The method as recited in claim 1, includingpivoting the variable vanes to navigate the variable vanes through thethroat regions free of contact with the blades of the end row.